Natural gas hydrates are a stable solid comprising water and natural gas, and have been known to scientists for some years as a curiosity. More recently, natural gas hydrates became a serious concern in regard to the transportation and storage of natural gas industries in cold climates, due to the tendency of hydrates to form in pipelines thereby blocking the flow the pipelines.
Natural gas hydrates may be formed by the combination of water and gas at relatively moderate temperatures and pressures, with the resulting solid having the outward characteristics of ice, being either white or grey in colour and cold to the touch. At ambient temperatures and pressures natural gas hydrates break down releasing natural gas.
Conventionally, gas storage is achieved through re-injecting into reservoirs, or pressurised reservoirs or through the use of line pack, where the volume of the pipeline system is of the same order of magnitude as several days' customer consumption. The use of natural gas hydrates in storage has the potential to provide a flexible way of storing reserves of natural gas to meet short to medium term requirements in the event of excessive demands or a reduction in the delivery of gas from source.
In any application, the gas content of the hydrate and the temperature at which the hydrate begins to decompose (i.e. the hydrate desolution temperature), are significant criteria that require consideration. Known natural gas hydrates exhibit a gas content of 163 Sm3 per m3 of hydrate, and a hydrate desolution temperature, at atmospheric pressure, of −15° C.
It is one object of the present invention to provide a natural gas hydrate and a method for the production thereof, with improved gas content and hydrate desolution temperature.
Throughout the specification, unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.